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a) 49 x ( X – 21 ) = 441 e) X : (12 + 13) = 7
X – 21 = 441:49 X : 25 = 7
X – 21 = 9 X = 7 x 25
X = 21 + 9 X = 175
X = 30
b) 53 x 31 x X = 4929 g) 429 : ( X + 31) = 11
31 x X = 4929 : 53 X + 31 = 429 : 11
31 x X = 93 X + 31 = 39
X = 93 : 31 ’ X = 39 – 31
X = 3 X = 8
c) 61 x (126 : X ) = 1281 h) 1 615 : (X x 19) = 17
126 : X = 1281 : 61 X x 19 = 1 615 : 17
126 : X = 21 X x 19 = 95
X = 126 : 21 X = 95 : 19
X = 6 X = 5
d) 79 x ( X : 23 ) = 316 i) 420 : ( X : 39 ) = 105
X : 23 = 316 : 79 X : 39 = 420 : 105
X : 23 = 4 X : 39 = 4
X = 4 x 23 X = 4 x 39
X = 92 X = 156
\(2016\times105-2016\times4-2016\)
\(=2016\times\left(105-4-1\right)\)
\(=2016\times100\)
\(=201600\)
\(x\times24+x\times6=240\)
\(x\times\left(24+6\right)=240\)
\(x\times30=240\)
\(x=240:30\)
\(x=8\)
\(x-167\times15=167\times185\)
\(x-2505=30895\)
\(x=30895+2505\)
\(x=33400\)
\(173\times105+173\times96-173\)
\(=173\times\left(105+96-1\right)\)
\(=173\times200\)
\(=34600\)
1. 2016 x 105 - 2016 x 4 - 2016
= 211680 - 8064 - 2016
= 203616 - 2016
= 201600
2. X x 24 + X x 6 = 240
X x (24 + 6) = 240
X x 30 = 240
X = 240 : 30
X = 8
3. X - 167 x 15 = 167 x 185
X - 2505 = 30895
X = 30895 - 2505
X = 28390
4. 173 x 105 + 173 x 96 - 173
= 18165 + 16608 - 173
= 34773 - 173
= 34600
b: =15/31(34/63-11/21)=15/31x1/63=5/651
a: \(=\dfrac{67}{63}\cdot5+\dfrac{11}{31}\cdot\dfrac{5}{7}=5\left(\dfrac{67}{63}+\dfrac{11}{31\cdot7}\right)=\dfrac{10880}{1953}\)
a)67/63 x 15/3 + 15/31 x 11/21
Thiếu đề
b)15/31 x 34/63 - 11/21 x 15/31
=15/31 x ( 34/63 -11/21)
= 15/31 x 1/63= 5/651
b: =15/31(34/63-11/21)=15/31x1/63=5/651
a: \(=\dfrac{67}{63}\cdot5+\dfrac{11}{31}\cdot\dfrac{5}{7}=5\left(\dfrac{67}{63}+\dfrac{11}{31\cdot7}\right)=\dfrac{10880}{1953}\)
b: =15/31(34/63-11/21)=15/31x1/63=5/651
a: =67/63⋅5+11/31⋅5/7=5(67/63+11/31⋅7)=10880/1953
Theo bài ra , ta có :
\(\frac{15}{x}=\frac{y}{21}=\frac{31}{105}\)
\(\Rightarrow x=5\)
Vì \(105:21=5\)
Nên \(\Rightarrow y=\frac{31}{15}\)
Vậy \(x=5;y=\frac{31}{15}\)
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